1. Field of the Invention
This invention relates generally to amplifier circuits with electronic gain control, and more particularly, to an amplifier susceptible to fabrication substantially in monolithic integrated circuit form in which logarithmic electronic gain control over a wide gain range may be effectively provided while maintaining temperature compensation independent of gain setting.
2. Description of the Prior Art
Sound amplification systems presently used often employ integrated circuits on a semiconductor chip with a resistor control potentiometer coupled to the IC circuitry for sound volume control. Since the human ear detects large changes in sound levels, it is desirable in some applications to provide a logarithmic gain control capable of varying the gain over a large range. In addition, for certain mobile communications applications it is desirable to utilize an electronic gain control so that the audio signal to be amplified does not pass through the control potentiometer. This avoids the need to send the audio signal through a control line thus eliminating the noise pick up which would otherwise occur. In the prior art, such logarithmic gain controlled amplifiers have a temperature dependence which increases with a decrease in gain that is unacceptable in many applications.